Activation of poly(ADP-ribose) polymerase contributes to development of doxorubicin-induced heart failure

Activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) by oxidant-mediated DNA damage is an important pathway of cell dysfunction and tissue injury in conditions associated with oxidative stress. Increased oxidative stress is a major factor implicated in the cardiotoxicity of doxorubicin (DOX), a widely used antitumor anthracycline antibiotic. Thus, we hypothesized that the activation of PARP may contribute to the DOX-induced cardiotoxicity. Using a dual approach of PARP-1 suppression, by genetic deletion or pharmacological inhibition with the phenanthridinone PARP inhibitor PJ34, we now demonstrate the role of PARP in the development of cardiac dysfunction induced by DOX. PARP-1+/+ and PARP-1-/- mice received a single injection of DOX (25 mg/kg i.p). Five days after DOX administration, left ventricular performance was significantly depressed in PARP-1+/+ mice, but only to a smaller extent in PARP-1-/- ones. Similar experiments were conducted in BALB/c mice treated with PJ34 or vehicle. Treatment with a PJ34 significantly improved cardiac dysfunction and increased the survival of the animals. In addition PJ34 significantly reduced the DOX-induced increase in the serum lactate dehydrogenase and creatine kinase activities but not metalloproteinase activation in the heart. Thus, PARP activation contributes to the cardiotoxicity of DOX. PARP inhibitors may exert protective effects against the development of severe cardiac complications associated with the DOX treatment.     

Activation of poly(ADP-ribose) polymerase in circulating leukocytes during myocardial infarction

Myocardial ischemia-reperfusion can lead to increased oxidative stress both locally and in circulating leukocytes. Oxidant-mediated DNA single strand breaks are known to activate the nuclear enzyme poly(ADP-ribose) polymerase (PARP) in various forms of shock, inflammation, and ischemia-reperfusion injury. The aim of the current study was to investigate whether a local insult such as myocardial ischemia-reperfusion is sufficient to lead to activation of PARP in circulating leukocytes. In anesthetized rats myocardial ischemia-reperfusion was induced by transient ligation of the left anterior descending coronary artery. There was a marked increase in poly(ADP-ribosyl)ation of proteins in homogenates of leukocytes isolated from rats at the end of the reperfusion period. Poly(ADP-ribosyl)ation was inhibited by administration of the pharmacologic PARP inhibitor INO-1001 (30 mg/kg) to the rats. We conclude that local insults, such as myocardial reperfusion injury, are sufficient to activate PARP in circulating leukocytes. PARP activation in circulating cells may mediate certain systemic effects of local ischemia-reperfusion injury such as inflammatory mediator production and remote organ injury.     

Poly(ADP-Ribose) polymerase promotes cardiac remodeling, contractile failure, and translocation of apoptosis-inducing factor in a murine experimental model of aortic banding and heart failure

Oxidant stress-induced activation of poly(ADP-ribose) polymerase (PARP) plays a role in the pathogenesis of various cardiovascular diseases. We have now investigated the role of PARP in the process of cardiac remodeling and heart failure in a mouse model of heart failure induced by transverse aortic constriction (banding). The catalytic activity of PARP was inhibited by the potent isoindolinone-based PARP inhibitor INO-1001 or by PARP-1 genetic deficiency. PARP inhibition prevented the pressure overload-induced decrease in cardiac contractile function, despite the pressure gradient between both carotid arteries being comparable in the two experimental groups. The development of hypertrophy, the formation of collagen in the hearts, and the mitochondrial-to-nuclear translocation of the cell death factor apoptosis-inducing factor (AIF) were attenuated by PARP inhibition. The ability of the inhibitor to block the catalytic activity of PARP was confirmed by immunohistochemical detection of poly(ADP-ribose), the product of the enzyme in the heart. Plasma levels of INO-1001, as measured at the end of the experiments, were in the concentration range sufficient to block the oxidant-mediated activation of PARP in murine cardiac myocytes in vitro. Myocardial hypertrophy and AIF translocation was also reduced in PARP-1-deficient mice undergoing aortic banding, compared with their wild-type counterparts. Overall, the current results demonstrate the importance of poly(ADP-ribos)ylation in the pathogenesis of banding-induced heart failure.     

Cyclophilin A participates in the nuclear translocation of apoptosis-inducing factor in neurons after cerebral hypoxia-ischemia

Upon cerebral hypoxia-ischemia (HI), apoptosis-inducing factor (AIF) can move from mitochondria to nuclei, participate in chromatinolysis, and contribute to the execution of cell death. Previous work (Cande, C., N. Vahsen, I. Kouranti, E. Schmitt, E. Daugas, C. Spahr, J. Luban, R.T. Kroemer, F. Giordanetto, C. Garrido, et al. 2004. Oncogene. 23:1514-1521) performed in vitro suggests that AIF must interact with cyclophilin A (CypA) to form a proapoptotic DNA degradation complex. We addressed the question as to whether elimination of CypA may afford neuroprotection in vivo. 9-d-old wild-type (WT), CypA(+/-), or CypA(-/-) mice were subjected to unilateral cerebral HI. The infarct volume after HI was reduced by 47% (P = 0.0089) in CypA(-/-) mice compared with their WT littermates. Importantly, CypA(-/-) neurons failed to manifest the HI-induced nuclear translocation of AIF that was observed in WT neurons. Conversely, CypA accumulated within the nuclei of damaged neurons after HI, and this nuclear translocation of CypA was suppressed in AIF-deficient harlequin mice. Immunoprecipitation of AIF revealed coprecipitation of CypA, but only in injured, ischemic tissue. Surface plasmon resonance revealed direct molecular interactions between recombinant AIF and CypA. These data indicate that the lethal translocation of AIF to the nucleus requires interaction with CypA, suggesting a model in which two proteins that normally reside in separate cytoplasmic compartments acquire novel properties when moving together to the nucleus.     

DNA修复蛋白PARP基因在大鼠缺血脑组织中的表达

目的　探讨大鼠局灶性脑缺血再灌注后DNA修复蛋白PARP基因表达的时空改变及其与凋亡的关系。方法　采用大鼠大脑中动脉阻塞再灌注模型 (MCAO R) ,运用原位杂交技术观察缺血再灌注PARPmRNA的时空分布 ,结合TUNEL技术观察其与凋亡的关系。结果　脑缺血 30min再灌注 1hPARPmRNA表达增加 ,随缺血或再灌注时间的延长表达逐渐增强 (P <0 0 5 ) ,与凋亡的时间变化规律相似 ,但范围大于并涵盖凋亡的范围 ,凋亡分布区外侧的缺血区表达也明显增加。结论　脑缺血 /再灌注损伤可诱导神经细胞DNA修复蛋白PARP基因的转录增强 ,PARP可能参与脑缺血损伤后的DNA修复。     

缺血预适应对糖尿病大鼠心肌梗死的影响

目的 :通过建立大鼠缺血预适应 (IP)模型 ,探讨IP对缺血 再灌注 (I/P)糖尿病大鼠心肌梗死的影响。方法 :向SD大鼠腹腔内注射链脲素 (6 0mg/kg)制造糖尿病大鼠模型。2天后 ,随机时刻测定血糖 ,将血糖≥ 13 9mmol/L定为糖尿病大鼠 2 0只 ,另外 2 0只血糖正常鼠为非糖尿病鼠。 2周后 ,麻醉大鼠 ,结扎和放松冠脉左前降支 (LAD)复制IP和I/P模型。将 40只大鼠分为IP糖尿病大鼠组 (DIP组 )、IP非糖尿病大鼠组 (NDIP组 )、非IP糖尿病大鼠组(DNIP组 )和非IP非糖尿病大鼠组 (NDNIP组 )各 10只。记录Ⅱ导联心电图。取心脏切片染色 ,计算心肌缺血范围和心肌梗死范围。结果 :各组间心肌缺血范围无显著差异 (P >0 0 5 )。DIP组心肌梗死范围较DNIP组明显减小 (P <0 0 1)。DNIP组室性心律失常增多 ,尤其室颤较其他各组显著增多 (P <0 0 1)。结论 :缺血预适应可以减轻糖尿病大鼠随后较长时间缺血 再灌注对心肌的严重损害 ,能减少心肌梗死范围和降低室颤的发生率。     

低氧训练与低氧大鼠心肌细胞凋亡及凋亡因子的表达

背景：低氧训练时,机体既要承受运动负荷,同时处于外界的低氧环境,此时,心组织将如何适应其变化？其机制研究国内外较少。目的：观察低氧与低氧训练对大鼠心肌细胞凋亡及Bax及Bcl-2表达的影响。方法：SD大鼠共60只随机分为6组,常氧组、低氧8h组、低氧12h组、常氧训练组、低氧8h训练组和低氧12h训练组,每组10只。后3组大鼠每天在坡度为0的动物跑台上以25m／min的速度训练1h。训练完后,将低氧8h组、低氧8h训练组和低氧12h组、低氧12h训练组放入氧体积分数为12．5％（相当于海拔4000m）的低氧舱内8h和12h。实验期为4周,5d／周。最后1次实验结束后24h,大鼠均实施速眠新II腹腔麻醉后取材,采用苏木精-伊红染色、原位末端脱氧核糖核苷酸转移酶介导的dUTP缺口末端标记法及蛋白免疫组织化学法检测各组大鼠心肌细胞凋亡和Bcl-2、Bax蛋白表达。结果与结论：①与常氧组相比,低氧12h组、常氧训练组、低氧训练组心肌细胞凋亡指数均显著增加（P〈0．05）;低氧12h训练组心肌细胞凋亡指数显著多于常氧训练组和低氧8h训练组（P〈0．05）。②与常氧组比较,其他各组Bcl-2、Bax、Bcl-2／Bax均显著性增高（P〈0．05）：常氧训练组Bcl-2、Bax、Bcl-2／Bax表达显著高于低氧8h组,显著低于低氧12h训练组（P〈0．05）;低氧12h训练组Bcl-2、Bax、Bcl-2／Bax表达比低氧12h组、低氧8h训练组显著增加（P〈0．05）。提示低氧、低氧训练可诱导大鼠心肌细胞Bcl-2、Bax蛋白表达,运动时低氧刺激与细胞凋亡率、凋亡指数及病理损伤有关,其中以低氧12h后运动训练组最明显,心肌细胞的凋亡调控与Bcl-2和Bax相关。     

Poly(adp-ribose) synthetase inhibition reduces bacterial translocation in rats after endotoxin challenge

We investigated whether 3-aminobenzamide (3-AB), a poly(ADP-ribose) synthetase (PARS) inhibitor, reduces bacterial translocation (BT) after intraperitoneal endotoxin administration. Wistar rats were randomized to receive intraperitoneal saline (control, n = 6); endotoxin (n = 8); 3-AB (n = 6); and 3-AB plus endotoxin (n = 8). Six hours later, to evaluate the endotoxin-related intestinal injury and BT, tissue and blood samples were collected. Administration of intraperitoneal endotoxin caused severe intestinal injury and BT to mesenteric lymph nodes. PARS inhibition with 3-AB completely prevented endotoxin-induced BT. No colony-forming bacteria was isolated from the samples obtained from 3-AB-pretreated animals under endotoxin challenge. Treatment with 3-AB significantly reduced the endotoxin-induced intestinal mucosal injury. The inhibition of PARS by its blocker 3-aminobenzamide during endotoxemia prevents bacterial translocation and intestinal injury in rats. PARS activation may provide a novel therapeutic approach in reducing gut barrier failure seen in endotoxemia.     

Inhibitors of poly(ADP-ribose) polymerase modulate signal transduction pathways and the development of bleomycin-induced lung injury

Poly(ADP-ribose) polymerase (PARP), a nuclear enzyme activated by strand breaks in DNA, plays an important role in the tissue injury associated with inflammation. The aim of our study was to evaluate the therapeutic efficacy of in vivo inhibition of PARP in an experimental model of lung injury caused by bleomycin administration. Mice subjected to intratracheal administration of bleomycin developed significant lung injury and apoptosis (measured by Annexin V coloration). An increase of immunoreactivity to nitrotyrosine and PARP, as well as a significant loss of body weight and mortality, was observed in the lung of bleomycin-treated mice. Administration of the two PARP inhibitors 3-aminobenzamide (3-AB) or 5-aminoisoquinolinone (5-AIQ) significantly reduced the 1) loss of body weight, 2) mortality rate, 3) infiltration of the lung with polymorphonuclear neutrophils (myeloperoxidase activity), 4) edema formation, and 5) histological evidence of lung injury. Administration of 3-AB and 5-AIQ also markedly reduced nitrotyrosine formation and PARP activation. These results demonstrate that treatment with PARP inhibitors reduces the development of inflammation and tissue injury events induced by bleomycin administration in the mice.     

急性心肌梗死中血小板活化因子水平的变化

目的 了解血小板活化因子(PAF)水平在急性心肌梗死这一病理过程中的变化,探讨急性心肌梗死过程中PAF与恶性心律失常等的关系.方法 (1)选取健康小型猪20只,使用球囊充气封堵前降支中远端1/3交界处,制作急性心肌梗死模型.分别在封堵前(基线期)、封堵后1 h抽取静脉血,测量PAF水平,同时记录心肌梗死后心律失常的情况.(2)选取经皮冠状动脉造影证实的急性心肌梗死患者72例,测定就诊即刻,24 h,48 h及72 h抽取血检测PAF水平;并记录72 h内患者心律失常事件及心源性休克情况.结果 (1)封堵前(基线期)PAF水平(4.66±2.89)ng/mL,封堵后1 hPAF水平为(6.00±2.82)ng/mL,封堵1 h后PAF升高值为(1.34±1.40)ng/mL,(P＜0.05);封堵后发生心律失常的小型猪(n=13)PAF升高值为(1.92±1.34)ng/mL,封堵后未发生心律失常的小型猪(n=7),其PAF升高值为(0.28±0.74)ng/mL,二者PAF升高值的差异具有统计学意义(P＜0.05).(2)急性心肌梗死患者在来院即刻,24 h,48 h及72 h的PAF水平分别为(0.47±0.05)ng/mL,(2.38±0.12)ng/mL,(3.65±0.15)ng/mL,(3.02±0.10)ng/mL;健康对照组PAF水平为(0.07±0.02)ng/mL(P＜0.05).72例急性心肌梗死患者中发生恶性心律失常、心力衰竭或心源性休克等并发症的患者40例(55%),其48 h的PAF水平为(4.72±0.16)ng/mL,无恶性心律失常、心衰或心源性休克的患者32例(45%),其来院后48 h的PAF水平为(2.31±0.03)ng/mL,二者差异具有统计学意义(P＜0.05).结论 急性心肌梗死后PAF水平明显升高,PAF水平越高,发生恶性心律失常、心衰或心源性休克概率越高.     

聚ADP核糖聚合酶抑制剂对重症急性胰腺炎大鼠肺炎症介质表达和肺损伤的影响

目的 探讨多聚腺苷酸二磷酸核糖聚合酶(PARP)抑制剂3-氨基苯甲酰胺(3-AB)对重症急性胰腺炎(SAP)肺损伤治疗作用的机制.方法 36只Wistar大鼠按随机数字法分为假手术对照组(SO组)、SAP组和3-AB处理组.采用5％牛磺胆酸钠逆行胰胆管注射法制备SAP模型,3-AB组在SAP造模前、后30 min分别经静脉注射3-AB (10 mg/kg).术后12 h测定血清淀粉酶、肺组织湿/干比、肺髓过氧化物酶(MPO)水平,光镜观察胰腺和肺脏病理变化,逆转录-聚合酶链反应法检测肺组织IL-1β和IL-6 mRNA表达,蛋白免疫印迹法检测肺组织TNF-α和ICAM-1蛋白表达.结果 SAP制模后血清淀粉酶、胰腺和肺损伤评分、肺组织湿/干比和MPO值,肺IL-1β和IL-6 mRNA的表达、TNF-α和ICAM-1蛋白表达水平均明显升高(P＜0.05).应用3-AB处理后,上述指标较SAP组均明显下降(P＜0.05).结论 PARP抑制剂3-AB可能通过抑制肺组织MPO,下调IL-1β、IL-6、TNF-α和ICAM-1等炎症介质的表达,对SAP肺损伤发挥保护和治疗作用.     

瑞舒伐他汀对糖尿病大鼠心肌梗死后心肌微血管形成的影响

目的:探讨瑞舒伐他汀对糖尿病大鼠心肌梗死后心肌微血管形成的影响.方法:将糖尿病大鼠随机分为3组:假手术组(A组)、心梗组(B组)、瑞舒伐他汀组(C组).行超声心动图检查;马松染色检测心肌纤维化、免疫组化检测血管内皮生长因子(VEGF)、CD31的表达;RT-PCR检测VEGF mRNA的表达.结果:与A组相比,B组左心室射血分数降低,左心室收缩末期(舒张末期)内径增大、心肌纤维化明显增加(均P＜0.05).与B组相比,C组左心室射血分数升高、左心室收缩末期(舒张末期)内径降低、心肌纤维化明显减少、心肌组织VEGF及CD31表达增加,心肌组织VEGF mRNA表达亦增加(均P＜0.05).结论:瑞舒伐他汀通过促进心肌组织血管形成,进而改善糖尿病大鼠心肌梗死后心功能,其机制可能与VEGF表达上调相关.     

Burn and smoke injury activates poly(ADP-ribose)polymerase in circulating leukocytes

The nuclear enzyme poly(ADP-ribose)polymerase (PARP) plays a significant role in the pathogenesis of various forms of critical illness. DNA strand breaks induced by oxidative and nitrative stress trigger the activation of PARP, and PARP, in turn, mediates cell death and promotes proinflammatory responses. Until recently, most studies focused on the role of PARP in solid organs such as heart, liver, and kidney. We investigated the effect of burn and smoke inhalation on the levels of poly(ADP-ribosylated) proteins in circulating sheep leukocytes ex vivo. Adult female merino sheep were subjected to burn injury (2× 20% each flank, 3 degrees) and smoke inhalation injury (insufflated with a total of 48 breaths of cotton smoke) under deep anesthesia. Arterial and venous blood was collected at baseline, immediately after the injury and 1 to 24 h after the injury. Leukocytes were isolated with the Histopaque method. The levels of poly(ADP-ribosyl)ated proteins were determined by Western blotting. The amount of reactive oxygen species was quantified by the OxyBlot method. To examine whether PARP activation continues to increase ex vivo in the leukocytes, blood samples were incubated at room temperature or at 37°C for 3 h with or without the PARP inhibitor PJ34. To investigate whether the plasma of burn/smoke animals may trigger PARP activation, burn/smoke plasma was incubated with control leukocytes in vitro. The results show that burn and smoke injury induced a marked PARP activation in circulating leukocytes. The activity was the highest immediately after injury and at 1 h and decreased gradually over time. Incubation of whole blood at 37°C for 3 h significantly increased poly(ADP-ribose) levels, indicative of the presence of an ongoing cell activation process. In conclusion, PARP activity is elevated in leukocytes after burn and smoke inhalation injury, and the response parallels the time course of reactive oxygen species generation in these cells.